This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A269280 #4 Feb 21 2016 09:00:45 %S A269280 0,236196,36673560,4684312584,542973139128,59587625651904, %T A269280 6310088238337128,651615466055490216,66042694681962193944, %U A269280 6597498728751383594736,651529527626284234223688 %N A269280 Number of 5Xn 0..3 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling three exactly once. %C A269280 Row 5 of A269276. %H A269280 R. H. Hardin, <a href="/A269280/b269280.txt">Table of n, a(n) for n = 1..210</a> %F A269280 Empirical: a(n) = 262*a(n-1) -25913*a(n-2) +1271424*a(n-3) -36373480*a(n-4) +662028380*a(n-5) -8018113210*a(n-6) +65608158980*a(n-7) -356568260410*a(n-8) +1185405035940*a(n-9) -1609856308508*a(n-10) -4162483461884*a(n-11) +23709461283851*a(n-12) -40474763971218*a(n-13) +272846513475*a(n-14) +106799477038956*a(n-15) -171480164894532*a(n-16) +115612142099328*a(n-17) -29562621871104*a(n-18) for n>23 %e A269280 Some solutions for n=2 %e A269280 ..1..0. .1..1. .0..0. .0..1. .1..1. .0..2. .0..1. .1..1. .0..2. .0..1 %e A269280 ..0..3. .0..1. .1..0. .2..0. .1..1. .1..1. .0..0. .0..1. .3..2. .3..2 %e A269280 ..1..3. .1..1. .1..3. .2..2. .1..0. .3..2. .0..0. .2..2. .2..3. .1..0 %e A269280 ..3..3. .2..0. .2..1. .3..1. .2..0. .3..3. .2..2. .0..2. .1..0. .1..1 %e A269280 ..1..0. .0..2. .0..0. .0..2. .2..1. .1..3. .1..0. .3..1. .3..2. .1..3 %Y A269280 Cf. A269276. %K A269280 nonn %O A269280 1,2 %A A269280 _R. H. Hardin_, Feb 21 2016